Conventionally, as a liquefied gas carrier ship which carries a liquefied natural gas (LNG) in a state where the gas is stored in a tank, there is known a liquefied gas carrier ship which includes a plurality of tanks disposed along the bow-stern direction, and one continuous tank cover which covers upper half portions of the plurality of tanks (see patent citation 1, for example).
Each flat spherical tank disclosed in patent citation 1 includes a circular cylindrical portion and a top portion continuously formed with the circular cylindrical portion above an equator portion. In patent citation 1, the flat spherical tank is configured such that, if a radius of the circular cylindrical portion is “R”, and a length of the top portion in the vertical direction is “H1”, an equation R/H1=1.5 is established. When the flat spherical tank is formed into such a shape, compared to a spherical tank having the same height, a large capacity can be maintained and, at the same time, wind pressure resistance can be reduced.
Patent Citation 1: Japanese Unexamined Patent Application, Publication No. 2012-56429